"""
SmartApp functionality to receive cloud-push notifications.

This module defines the functions to manage the SmartApp integration
within the SmartThings ecosystem in order to receive real-time webhook-based
callbacks when device states change.
"""
import asyncio
import functools
import logging
from urllib.parse import urlparse
from uuid import uuid4

from aiohttp import web

from homeassistant.components import cloud, webhook
from homeassistant.const import CONF_WEBHOOK_ID
from homeassistant.helpers.aiohttp_client import async_get_clientsession
from homeassistant.helpers.dispatcher import (
    async_dispatcher_connect, async_dispatcher_send)
from homeassistant.helpers.typing import HomeAssistantType

from .const import (
    APP_NAME_PREFIX, APP_OAUTH_CLIENT_NAME, APP_OAUTH_SCOPES, CONF_APP_ID,
    CONF_CLOUDHOOK_URL, CONF_INSTALLED_APP_ID, CONF_INSTALLED_APPS,
    CONF_INSTANCE_ID, CONF_LOCATION_ID, CONF_REFRESH_TOKEN, DATA_BROKERS,
    DATA_MANAGER, DOMAIN, SETTINGS_INSTANCE_ID, SIGNAL_SMARTAPP_PREFIX,
    STORAGE_KEY, STORAGE_VERSION)

_LOGGER = logging.getLogger(__name__)


async def find_app(hass: HomeAssistantType, api):
    """Find an existing SmartApp for this installation of hass."""
    apps = await api.apps()
    for app in [app for app in apps
                if app.app_name.startswith(APP_NAME_PREFIX)]:
        # Load settings to compare instance id
        settings = await app.settings()
        if settings.settings.get(SETTINGS_INSTANCE_ID) == \
                hass.data[DOMAIN][CONF_INSTANCE_ID]:
            return app


async def validate_installed_app(api, installed_app_id: str):
    """
    Ensure the specified installed SmartApp is valid and functioning.

    Query the API for the installed SmartApp and validate that it is tied to
    the specified app_id and is in an authorized state.
    """
    from pysmartthings import InstalledAppStatus

    installed_app = await api.installed_app(installed_app_id)
    if installed_app.installed_app_status != InstalledAppStatus.AUTHORIZED:
        raise RuntimeWarning("Installed SmartApp instance '{}' ({}) is not "
                             "AUTHORIZED but instead {}"
                             .format(installed_app.display_name,
                                     installed_app.installed_app_id,
                                     installed_app.installed_app_status))
    return installed_app


def validate_webhook_requirements(hass: HomeAssistantType) -> bool:
    """Ensure HASS is setup properly to receive webhooks."""
    if cloud.async_active_subscription(hass):
        return True
    return get_webhook_url(hass).lower().startswith('https://')


def get_webhook_url(hass: HomeAssistantType) -> str:
    """
    Get the URL of the webhook.

    Return the cloudhook if available, otherwise local webhook.
    """
    cloudhook_url = hass.data[DOMAIN][CONF_CLOUDHOOK_URL]
    if cloud.async_active_subscription(hass) and cloudhook_url is not None:
        return cloudhook_url
    return webhook.async_generate_url(hass, hass.data[DOMAIN][CONF_WEBHOOK_ID])


def _get_app_template(hass: HomeAssistantType):
    from pysmartthings import APP_TYPE_WEBHOOK, CLASSIFICATION_AUTOMATION

    endpoint = "at " + hass.config.api.base_url
    cloudhook_url = hass.data[DOMAIN][CONF_CLOUDHOOK_URL]
    if cloudhook_url is not None:
        endpoint = "via Nabu Casa"
    description = "{} {}".format(hass.config.location_name, endpoint)

    return {
        'app_name': APP_NAME_PREFIX + str(uuid4()),
        'display_name': 'Home Assistant',
        'description': description,
        'webhook_target_url': get_webhook_url(hass),
        'app_type': APP_TYPE_WEBHOOK,
        'single_instance': True,
        'classifications': [CLASSIFICATION_AUTOMATION]
    }


async def create_app(hass: HomeAssistantType, api):
    """Create a SmartApp for this instance of hass."""
    from pysmartthings import App, AppOAuth, AppSettings
    from pysmartapp.const import SETTINGS_APP_ID

    # Create app from template attributes
    template = _get_app_template(hass)
    app = App()
    for key, value in template.items():
        setattr(app, key, value)
    app, client = await api.create_app(app)
    _LOGGER.debug("Created SmartApp '%s' (%s)", app.app_name, app.app_id)

    # Set unique hass id in settings
    settings = AppSettings(app.app_id)
    settings.settings[SETTINGS_APP_ID] = app.app_id
    settings.settings[SETTINGS_INSTANCE_ID] = \
        hass.data[DOMAIN][CONF_INSTANCE_ID]
    await api.update_app_settings(settings)
    _LOGGER.debug("Updated App Settings for SmartApp '%s' (%s)",
                  app.app_name, app.app_id)

    # Set oauth scopes
    oauth = AppOAuth(app.app_id)
    oauth.client_name = APP_OAUTH_CLIENT_NAME
    oauth.scope.extend(APP_OAUTH_SCOPES)
    await api.update_app_oauth(oauth)
    _LOGGER.debug("Updated App OAuth for SmartApp '%s' (%s)",
                  app.app_name, app.app_id)
    return app, client


async def update_app(hass: HomeAssistantType, app):
    """Ensure the SmartApp is up-to-date and update if necessary."""
    template = _get_app_template(hass)
    template.pop('app_name')  # don't update this
    update_required = False
    for key, value in template.items():
        if getattr(app, key) != value:
            update_required = True
            setattr(app, key, value)
    if update_required:
        await app.save()
        _LOGGER.debug("SmartApp '%s' (%s) updated with latest settings",
                      app.app_name, app.app_id)


def setup_smartapp(hass, app):
    """
    Configure an individual SmartApp in hass.

    Register the SmartApp with the SmartAppManager so that hass will service
    lifecycle events (install, event, etc...).  A unique SmartApp is created
    for each SmartThings account that is configured in hass.
    """
    manager = hass.data[DOMAIN][DATA_MANAGER]
    smartapp = manager.smartapps.get(app.app_id)
    if smartapp:
        # already setup
        return smartapp
    smartapp = manager.register(app.app_id, app.webhook_public_key)
    smartapp.name = app.display_name
    smartapp.description = app.description
    smartapp.permissions.extend(APP_OAUTH_SCOPES)
    return smartapp


async def setup_smartapp_endpoint(hass: HomeAssistantType):
    """
    Configure the SmartApp webhook in hass.

    SmartApps are an extension point within the SmartThings ecosystem and
    is used to receive push updates (i.e. device updates) from the cloud.
    """
    from pysmartapp import Dispatcher, SmartAppManager

    data = hass.data.get(DOMAIN)
    if data:
        # already setup
        return

    # Get/create config to store a unique id for this hass instance.
    store = hass.helpers.storage.Store(STORAGE_VERSION, STORAGE_KEY)
    config = await store.async_load()
    if not config:
        # Create config
        config = {
            CONF_INSTANCE_ID: str(uuid4()),
            CONF_WEBHOOK_ID: webhook.generate_secret(),
            CONF_CLOUDHOOK_URL: None
        }
        await store.async_save(config)

    # Register webhook
    webhook.async_register(hass, DOMAIN, 'SmartApp',
                           config[CONF_WEBHOOK_ID], smartapp_webhook)

    # Create webhook if eligible
    cloudhook_url = config.get(CONF_CLOUDHOOK_URL)
    if cloudhook_url is None \
            and cloud.async_active_subscription(hass) \
            and not hass.config_entries.async_entries(DOMAIN):
        cloudhook_url = await cloud.async_create_cloudhook(
            hass, config[CONF_WEBHOOK_ID])
        config[CONF_CLOUDHOOK_URL] = cloudhook_url
        await store.async_save(config)
        _LOGGER.debug("Created cloudhook '%s'", cloudhook_url)

    # SmartAppManager uses a dispatcher to invoke callbacks when push events
    # occur. Use hass' implementation instead of the built-in one.
    dispatcher = Dispatcher(
        signal_prefix=SIGNAL_SMARTAPP_PREFIX,
        connect=functools.partial(async_dispatcher_connect, hass),
        send=functools.partial(async_dispatcher_send, hass))
    # Path is used in digital signature validation
    path = urlparse(cloudhook_url).path if cloudhook_url else \
        webhook.async_generate_path(config[CONF_WEBHOOK_ID])
    manager = SmartAppManager(path, dispatcher=dispatcher)
    manager.connect_install(functools.partial(smartapp_install, hass))
    manager.connect_update(functools.partial(smartapp_update, hass))
    manager.connect_uninstall(functools.partial(smartapp_uninstall, hass))

    hass.data[DOMAIN] = {
        DATA_MANAGER: manager,
        CONF_INSTANCE_ID: config[CONF_INSTANCE_ID],
        DATA_BROKERS: {},
        CONF_WEBHOOK_ID: config[CONF_WEBHOOK_ID],
        # Will not be present if not enabled
        CONF_CLOUDHOOK_URL: config.get(CONF_CLOUDHOOK_URL),
        CONF_INSTALLED_APPS: []
    }
    _LOGGER.debug("Setup endpoint for %s",
                  cloudhook_url if cloudhook_url else
                  webhook.async_generate_url(hass, config[CONF_WEBHOOK_ID]))


async def unload_smartapp_endpoint(hass: HomeAssistantType):
    """Tear down the component configuration."""
    if DOMAIN not in hass.data:
        return
    # Remove the cloudhook if it was created
    cloudhook_url = hass.data[DOMAIN][CONF_CLOUDHOOK_URL]
    if cloudhook_url and cloud.async_is_logged_in(hass):
        await cloud.async_delete_cloudhook(
            hass, hass.data[DOMAIN][CONF_WEBHOOK_ID])
        # Remove cloudhook from storage
        store = hass.helpers.storage.Store(STORAGE_VERSION, STORAGE_KEY)
        await store.async_save({
            CONF_INSTANCE_ID: hass.data[DOMAIN][CONF_INSTANCE_ID],
            CONF_WEBHOOK_ID: hass.data[DOMAIN][CONF_WEBHOOK_ID],
            CONF_CLOUDHOOK_URL: None
        })
        _LOGGER.debug("Cloudhook '%s' was removed", cloudhook_url)
    # Remove the webhook
    webhook.async_unregister(hass, hass.data[DOMAIN][CONF_WEBHOOK_ID])
    # Disconnect all brokers
    for broker in hass.data[DOMAIN][DATA_BROKERS].values():
        broker.disconnect()
    # Remove all handlers from manager
    hass.data[DOMAIN][DATA_MANAGER].dispatcher.disconnect_all()
    # Remove the component data
    hass.data.pop(DOMAIN)


async def smartapp_sync_subscriptions(
        hass: HomeAssistantType, auth_token: str, location_id: str,
        installed_app_id: str, devices):
    """Synchronize subscriptions of an installed up."""
    from pysmartthings import (
        CAPABILITIES, SmartThings, SourceType, Subscription,
        SubscriptionEntity
    )

    api = SmartThings(async_get_clientsession(hass), auth_token)
    tasks = []

    async def create_subscription(target: str):
        sub = Subscription()
        sub.installed_app_id = installed_app_id
        sub.location_id = location_id
        sub.source_type = SourceType.CAPABILITY
        sub.capability = target
        try:
            await api.create_subscription(sub)
            _LOGGER.debug("Created subscription for '%s' under app '%s'",
                          target, installed_app_id)
        except Exception:  # pylint:disable=broad-except
            _LOGGER.exception("Failed to create subscription for '%s' under "
                              "app '%s'", target, installed_app_id)

    async def delete_subscription(sub: SubscriptionEntity):
        try:
            await api.delete_subscription(
                installed_app_id, sub.subscription_id)
            _LOGGER.debug("Removed subscription for '%s' under app '%s' "
                          "because it was no longer needed",
                          sub.capability, installed_app_id)
        except Exception:  # pylint:disable=broad-except
            _LOGGER.exception("Failed to remove subscription for '%s' under "
                              "app '%s'", sub.capability, installed_app_id)

    # Build set of capabilities and prune unsupported ones
    capabilities = set()
    for device in devices:
        capabilities.update(device.capabilities)
    capabilities.intersection_update(CAPABILITIES)

    # Get current subscriptions and find differences
    subscriptions = await api.subscriptions(installed_app_id)
    for subscription in subscriptions:
        if subscription.capability in capabilities:
            capabilities.remove(subscription.capability)
        else:
            # Delete the subscription
            tasks.append(delete_subscription(subscription))

    # Remaining capabilities need subscriptions created
    tasks.extend([create_subscription(c) for c in capabilities])

    if tasks:
        await asyncio.gather(*tasks)
    else:
        _LOGGER.debug("Subscriptions for app '%s' are up-to-date",
                      installed_app_id)


async def smartapp_install(hass: HomeAssistantType, req, resp, app):
    """
    Handle when a SmartApp is installed by the user into a location.

    Create a config entry representing the installation if this is not
    the first installation under the account, otherwise store the data
    for the config flow.
    """
    install_data = {
        CONF_INSTALLED_APP_ID: req.installed_app_id,
        CONF_LOCATION_ID: req.location_id,
        CONF_REFRESH_TOKEN: req.refresh_token
    }
    # App attributes (client id/secret, etc...) are copied from another entry
    # with the same parent app_id.  If one is not found, the install data is
    # stored for the config flow to retrieve during the wait step.
    entry = next((
        entry for entry
        in hass.config_entries.async_entries(DOMAIN)
        if entry.data[CONF_APP_ID] == app.app_id), None)
    if entry:
        data = entry.data.copy()
        data.update(install_data)
        # Add as job not needed because the current coroutine was invoked
        # from the dispatcher and is not being awaited.
        await hass.config_entries.flow.async_init(
            DOMAIN, context={'source': 'install'},
            data=data)
    else:
        # Store the data where the flow can find it
        hass.data[DOMAIN][CONF_INSTALLED_APPS].append(install_data)

    _LOGGER.debug("Installed SmartApp '%s' under parent app '%s'",
                  req.installed_app_id, app.app_id)


async def smartapp_update(hass: HomeAssistantType, req, resp, app):
    """
    Handle when a SmartApp is updated (reconfigured) by the user.

    Store the refresh token in the config entry.
    """
    # Update refresh token in config entry
    entry = next((entry for entry in hass.config_entries.async_entries(DOMAIN)
                  if entry.data.get(CONF_INSTALLED_APP_ID) ==
                  req.installed_app_id),
                 None)
    if entry:
        entry.data[CONF_REFRESH_TOKEN] = req.refresh_token
        hass.config_entries.async_update_entry(entry)

    _LOGGER.debug("Updated SmartApp '%s' under parent app '%s'",
                  req.installed_app_id, app.app_id)


async def smartapp_uninstall(hass: HomeAssistantType, req, resp, app):
    """
    Handle when a SmartApp is removed from a location by the user.

    Find and delete the config entry representing the integration.
    """
    entry = next((entry for entry in hass.config_entries.async_entries(DOMAIN)
                  if entry.data.get(CONF_INSTALLED_APP_ID) ==
                  req.installed_app_id),
                 None)
    if entry:
        # Add as job not needed because the current coroutine was invoked
        # from the dispatcher and is not being awaited.
        await hass.config_entries.async_remove(entry.entry_id)

    _LOGGER.debug("Uninstalled SmartApp '%s' under parent app '%s'",
                  req.installed_app_id, app.app_id)


async def smartapp_webhook(hass: HomeAssistantType, webhook_id: str, request):
    """
    Handle a smartapp lifecycle event callback from SmartThings.

    Requests from SmartThings are digitally signed and the SmartAppManager
    validates the signature for authenticity.
    """
    manager = hass.data[DOMAIN][DATA_MANAGER]
    data = await request.json()
    result = await manager.handle_request(data, request.headers)
    return web.json_response(result)